Method of reinforcing building units



Mfll'fih H, 1941 F. 0, ANDEREGG; 2,234,6fi3

METHOD OF REINFORCING BUILDING UNITS Filed Sept. 21, 1935 Fi .1. v

i utented Mar. 11, 1941 NITED STATES PATENT OFFICE I 2,234,663 METHOD OF REINFORCING BUILDING UNITS Frederick 0. Anderegg, Mount Union, Pa.

Application September 21, 1935, Serial No. 41,573 6 Claims. (c1. 25-154) Hiittemann and Wolfgang Czernin, #1332371 dated October 31, 1933, entitled Method of making light weight blocks, there is described the method of making light weight heat-insulating building blocks from a mixture of finely pulverlld ized siliceous and calcareous materials, the result being highly porous blocks, each comprising a three-dimensional skeleton network of readily frangible calcium hydrosilicate. Such blocks, from the standpoint of insulating value are adit mirably adapted for use in building constructions, but, because of limitations in strength, have little structural value, this holding true especially for the comparatively large slab units.

The method of the present invention is de- 2d signed primarily for the production, in connection with the method of the stated patent, of

reinforced slab building units, light in weight and high in insulating value.

In producing the light weight composition ma- 25 terial pursuant to the disclosure of the patent, the mixed constituent materials, at an advanced stage of preparation, 1. e, at the stage immediately following molding to the form of the final product, are subjected to heat induration adto vantageously artificially supplied at an elevated temperature, and preferably by the application thereto of steam under pressure. Under the action of such heat induration, a highly porous, hard but readily frangible three-dimensional 35 skeleton network oi." calcium hydrosilicate is formed. Upon formation, the skeleton network is filled with moisture resulting from the chemical reaction. It is principally at this stage that the method of the present invention is 40 applied.

Essentially, as applied to the above material, the preferred method of this invention com.- prises incorporating suitable reinforcing means, such as steel rods, in the material forming the 45 body member of the unit, prior to the stage of formation of the.hard skeleton network, and maintaining such reinforcing means under tension during the formation of the skeleton network without thereby stressing the chemically 50 active composition material. Thereafter, and during the cooling and drying stage of the cal cium hydrosilicate skeleton network slab, the tension stress of the reinforcing means is transferred to compressive stress of the body member.

55 After completion of the cooling and drying stage,

the reinforcing means may be additional tension stressed, effecting a pre-stress of the unit to a degree structurally advantageous.

Because of thecognpressive force exerted on the body member during the cooling and drying 5 stage, such cooling and drying may be accomplished rapidly in any suitable manner without structural injury to the cementitious composition material, and in fact, producing a highly porous three-dimensional skeleton network body member having strength and cohesion superior to that which it would otherwise have.

In its preferred practice, the method contemplates the use of substantially cylindrical rods of steel having a yield point of approximately 18 50,000 pounds per square inch. These rods are so placed within a suitable form-box as to extend across the same between two opposite end thereof, the rod-ends being threaded and extending through and beyond the stated ends of 20 the form-box for the reception of tensioning nuts.

Inside the form-box are plates loosely strung on the rods adjacent the stated o posite ends of the form-box and configurated according to a cross-section of the desired slab. The plates are respectively separated from such form-box ends by nuts threaded on the rods.

The rods are initially tensioned by tightening the securing nuts against their contiguous form-box ends; whereupon, the plastic cementitious material is poured into the form-box between the stated plates. Upon settlng of the cementitious material, the securing nuts and the form-box are removed, allowing the initial tension of the rods to manifest itself as compressive stress on the hardened cementitious material by reason of the bearing of the plates against the stated separating nuts. Such compressive, stress is maintained during the final drying treatment of the cementitlous material. Thereafter, the separating nuts may be tightened against the plates to tension the reinforcing ends and thus impart a predetermined pre-stress to the 4 structural unit.

The reinforcing'rods may be incorporated in, the cementitious slab adjacent one or both faces, the positioning and the tensioning thereof being determined by the nature of the actual load the structural unit will carry in practice.

For example, in the case of floor slabs, which are designed to be combined joist and insulation, the rods on the under side are tightened to place the material under a compressive load is of from approximately A, to $6 of its compressive strength.

An object oi my invention, therefore, is an improved method of reinforcing building units.

Another object is an improved method of preventing distortion in, and injury to, building units which are formed pursuant to the disclosure of U. S. Patent No. 1,932,971, during the cooling and drying thereof in the course of manufacture.

A further object is an improved reinforced building unit composed of relatively light material.

In the accompanying drawing,

Fig. 1 is a perspective view of an improved reinforced building unit, partly in section, and constructed in accordance with my improved method.

Fig. 2 is a sectional elevation through a molding form and through a building unit, showing the method of initially tensioning the reinforcing rods, and

Fig. 3 is a sectional elevation of a building unit after removal thereof from the form.

.Referring to the drawing, Fig. 2, lil designates a iioor or bed plate, of any desired superficial area, constituting the bottom of the mold or form-box in which the improved building units are constructed.

Secured to the top face of the floor or bed plate ii], in any suitable manner, is the mold or formbox it, usually rectangular in shape. In the present instance, the length of the form is greater than the length of the building unit t2, but the width is e ual thereto. One end of the form M, as at G3, is removably secured to the door or bed plate it], for a purpose to be hereinafter described.

The building unit i2 representing one phase of the present invention, is shaped within the form it. It may be of any desired thickness and linear dimensions. I have shown a building unit in the drawing of such thickness that reinforcing rods M are advantageously placed adjacent each major iace thereof. At each end of the form if], is placed a plate i5, having a length and breadth equal, respectively, to the width and thickness of the proposed building unit 02. Such plates 95 are provided with perforations it sufiiciently large to permit the ends of reinforcing rods i to pass therethrough.

Corresponding perforations B6 in the plates it are in alignment with each other, to insure parallel placement of the reinforcing rods i The respective ends of the reinforcing rods I l are threaded, as indicated at ill, to receive nuts l8 and iii. The nuts l8 abut against the plates l5, and the nuts is abut against the re spective outer faces of opposite end members of the form l i.

In carrying out my improved method, the re-- inforcing rods l6 are passed through the perforations it in the plates 55, and the nuts it are threaded into position against the outer faces of the plates 55. The reinforcing rods M are then passed through the perforations in the form it, and through the removably secured end it of the form. The nuts 59 are then threaded onto the threaded ends ii of the reinforcing rods 84 against the outer face of the form members.

As the nuts it are screwed onto the reinforcing rods M, the said rods are placed under tension. The tension may be anything desired, with in the limits of the strength of the materials.

The rods l l being tensioned, the proper material is poured into the form it, to form the slab l2, and the slab allowed to attain a preliminary set. The nuts l9 are then removed from the threaded ends or the reinforcing rods l4, thus permitting the tension in the rods It to be exerted on the plates it through the nuts l8. The complete setting and final drying of the slab l2 may be accelerated as fast as is necessary, or desirable, and it has been found that no deleterious efiects are produced thereby.

The product resulting from the above described process is free from cracks, is homogeneous in structure, and the reinforcing permits it to be subjected to relatively rough treatment without apparent injury, either facial or structural.

Various modifications will readily suggest themselves to those skilled in this art and I therefore am not to be limited other than as pointed out in the appended claims. For example, the specified means for prestressing the reinforcing rods are merely illustrative. Various other devices for performing this operation, and placing the prestressed rods in relative position to the slab, both before and after casting, will readily suggest themselves to those skilled in the art.

After the drying, the nuts it are advantageously turned down to stretch the rods it again, placing the material 92 under compression up to 159 or 200 pounds per square inch. The amount of compression may be accurately determined and controlled by measuring the stretch in the rods 1.

The above step in the prestressing produces a surprising increase in stiffness, in resistance to bending loads, and in resistance to impact. For example, slabs have been made of the light weight material of the stated patent with the following dimensions: length 96 inches, width 30 inches, thickness 2 inches. The light weight ma terial had a tensile strength of about 100 pounds per square inch, and a fiexural strength of about 269 pounds per square inch.

Such slabs successfully withstood the impact of a ZOO-pound man iumpingup and down on the middle of the slab, the slab being supported at its ends. Even when the impact was sufiicient to exceed the pro-stress strength, thereby permitting the under side of the slab to open in tension, the slab resumed its normal state upon removing the load.

While the method of the invention is particularly advantageous as applied in connection with the method and material of the aforementioned patent, its application from a-generic standpoint is by no means restricted thereto, being advantageous in its application to any cementitious material raising generally similar problems to those of the material of the patent.

I claim:

l. A method of producing a light weight reinforced structural building unit of a cementitious mixture of a type which, upon setting, will produce highly porous body, comprising casting the plastic cementitious mixture around reinforcing means maintained under tension, and allowing the cast cementitious mixture to take its initial set only while preventing the said tension from stressing the said cast cementitious mixture, thereafter transferring the tension stress of said reinforcing means to compressive stress of the set cementitious mixture; and maintaining said compressive stress while the mixture attains its final set.

2. A method as recited in claim 1 wherein the stated reinforcing means are additionally teniii till

Bill

sinned to a predetermined extent after the stated cementitious mixture has attained its final set whereby the resulting unitis structurally prestressed. I

3. A method oi producing 9. reinforced structurei huildine unit or light-weight highly porous cherncter from u mixture of finely divided sillcious end calcareous material that has been processed to o stage requiring only the application oi heot thereto to complete the formation oi n herd, highly porous, three-dimensional sheieton networir oi calcium hydrosilicute, which comprises molding the so processed mnterinl to nnei unit iorm around tensioneci reiniorcine menus while preventing the tension oi seid re iniorcine menus irom stressing sold materiel,

subjecting: the so molded unit to heat indurotion to complete the iormution of the highly porous, three-dimcnsionni skeleton networir oi eeicium hydrosilicote, thereafter trensferrinn the tension stress of said reiniorcine' menus to compressive stress oi the sold three-dimensionoi sheieton net work of cnlciurn hydrosilicete, end coolinn end drying sold three-dimensionel skeleton network oi calcium hydrosilicete while maintaining the compressive stress thereoi.

i. A method es recited in claim 3 wherein the started reinforcing means ere additionelly tensioneci to u predetermined extent sifter the stated cooling and drying treatment of the-set cementitious material has been carried to conclusion whereby the resulting unit is structurally prestressed.

' 5. A method oi producing e reinforced stmcturei building unit of linht-weight highly porous character from u cementitious mixture that hes been processed to o store recuirine -only the application oi heat thereto to complete the formotion oi n herd, highly porous, three-dimensionnl skeleton networir, which comprises molding the so processed mixture to him]. unit iorm nround tensioned reiniorcine moons while preventing the tension oi sold reiniorcinn meens irorn stressing snid mixture, suhiectinu the so molded unit to host indurettion to complete the iormntion oi the hinhly porous, thine-dimensionoi sireieton networh, thereniter trnnsferrintr the tension stress oi said reinforciny menus to compressive stress oi the said three-dimensionni sireleton networlr; end cooling nnd dryinn seid three-dirnensionel sireieton networi; while merintnininrr the compressive stress thereof.

ii. n method us recited in claim 5 wherein the WEDWICK U. ANDEREGG. 

